Rigid, hinged-lid packets of cigarettes are currently the most widely marketed, by being easy to produce, practical and easy to use, and by effectively protecting the cigarettes inside.
A rigid, hinged-lid packet of cigarettes comprises an inner package defined by a group of cigarettes wrapped in a sheet of foil inner wrapping; and a rigid outer package housing the inner package. The outer package comprises a cup-shaped container housing the group of cigarettes and having an open top end; and a cup-shaped lid hinged to the container along a hinge to rotate, with respect to the container, between an open and a closed position opening and closing the open end respectively.
Tobacco is highly sensitive to environment. That is, in contact with the atmosphere, its organic characteristics tend to vary alongside variations in humidity (by losing or absorbing too much moisture) or due to evaporation of the volatile substances with which the tobacco is impregnated (especially in the case of aromatic cigarettes treated with spices such as cloves). To preserve the tobacco, packets of cigarettes are therefore cellophane-wrapped, i.e. wrapped in a heat-sealed overwrapping of airtight plastic material. This, however, may not always be sufficient to fully preserve the tobacco in the packet, especially if the packet is consumed some time after manufacture. Moreover, when the packet is unsealed, the overwrapping is removed at least partly, thus exposing the tobacco to the atmosphere, and, if the cigarettes are not consumed soon after the packet is unsealed, the organic characteristics of the remaining cigarettes may deteriorate visibly.
In an attempt to eliminate this drawback, rigid packets of cigarettes have been proposed in which the inner package is airtight, is heat sealed, and comprises a sheet of airtight inner wrapping.
One problem of rigid packets of cigarettes, in which the inner package comprises a sheet of airtight wrapping, is that, once some of the cigarettes are removed, the inner package tends to collapse, thus making it difficult to withdraw the remaining cigarettes. Moreover, when heat sealing the superimposed portions of the sheet of airtight inner wrapping, the cigarettes are subjected to mechanical stress that may result in local deformation and/or tobacco fallout, and to thermal stress that may deteriorate the tobacco locally.
To solve this problem, it has been proposed, e.g. in MOLINS LTD U.S. Pat. No. 3,999,655 and HAUNI WERKE KOERBER & CO KG Patent DE4330006, to insert a rigid collar, comprising a cardboard stiffener, inside the inner package and about the group of cigarettes to maintain the correct shape of the inner package and protect the cigarettes when folding and heat sealing the sheet of airtight inner wrapping. However, placing and folding a rigid collar of the type currently marketed about the group of cigarettes before folding the sheet of inner wrapping about the group of cigarettes is extremely complex on a standard packing machine, so producing this type of packet calls for a special packing machine that is much more expensive than an equivalent standard packing machine.